Aneroid precision barometer having 5½” silvered and machine engraved dial with mirrored parallax ring, twin scales calibrated in inches of mercury and millibars with ranges 26 – 31 and 750 – 1085 respectively read dual rotation. Centre marked “Pressure in Millibars and Inches of Mercury,” and “Barometer ML-102-E.” Blackened aluminium pointer having blade terminus. Heavy perspex glass. Twin 2¼” capsule driven movement with sector-actuated arbour set in jewelled bearings, invar brass compensation. Mounted within a brass casting and screwed to a bronze plate with gear teeth cut to the circumference, the assembly rotated for adjustment via meshing worm drive, the head with screw slot.

Contained and mounted upon rubber bushes within its pressed steel, green crackle finished steel case with applied label stating: “Signal Corps Barometer ML-102-E,” serial no. “173:CJF,” and “41-day-44.” Transverse calibration screw to lower front, suspension point at top. Nomograph chart to verso.

All contained within a contemporary heavy brown leather and maroon velvet lined  protective case, lower hinged rear flap on four short straps on popper fastenings.

Specifically built for the United States military to an extremely high standard, the movement is very unusual, great attention having been paid to sensitivity and accuracy witnessed by jewelled bearings to the arbour – an unusual improvement. Apparently designed as an altimeter, this instrument issued to the Signal Corps may well have been employed in the determination of atmospheric conditions effecting radio transmission and reception (depending on wavelength and prevailing atmospheric conditions, radio signal propagation can be substantially affected). The millibars scale is unusually wide – this is read on dual concentric scales with two rotations of the pointer required for the full range.

The case retaining virtually all its original crackle finish, the dial clean and crisp. The leather transport case with marks, minor abrasions and discolouring, the velvet interior with minor losses. Overall sound.

Issued during World War II, this is an interesting and very collectable instrument. It would have originally been issued with a green canvas carry case – this one is housed in the much more robust and expensive leather case that was issued with the ML-102-B barometer of identical dimensions.

Serviced and calibrated, this military precision barometer is in good working order.